The long-term goal of this project is to understand the molecular mechanism of translation in terms of the three-dimensional structure of the ribosome and its interactions with its functional ligands. The purpose is to determine the structure of Thermus thermophilus 70S ribosomes, in complex with mRNA, tRNAs and translational factors in different states of the translational elongation cycle. The immediate goal is to study several functional co-crystal complexes at medium (ca. 9Angstrom units) resolution. The longer-term plan is to then focus on the most promising candidate for solution at much higher (ca. 3Angstrom units) resolution. It is expected that these results will not only provide a sound structural basis for understanding the mechanism of translation at the molecular level, but will also reveal a wealth of information about RNA structure and protein-RNA interactions in general.